A sensitive and specific sandwich ELISA was developed for the diagnosis of Glanzmann's thrombasthenia (GT) and the heterozygote carriers of the disease using whole blood platelets. The assay used anti-CD36 antibody to capture platelets from platelet-rich plasma which was subsequently treated with a bioengineered disintegrin/alkaline phosphatase hybrid protein specific for GP IIb/IIIa. The test allows large number of samples to be typed and can also be used on stored samples. The assay correctly diagnosed 40 normal healthy individuals, 10 GT cases, 10 heterozygotes, 3 Bernard-Soulier syndrome cases and 2 type 3 GT cases. ELISA plates were stable at room temperature up to 3 weeks without any loss of activity. This novel and simple test can be widely used for heterozygote detection besides diagnosing GT cases without using a sophisticated flow cytometer or a platelet aggregometer and has wide applicability in countries like India where many of these cases remain undiagnosed due to the lack of diagnostic facilities.